1. Field of the Invention
The present invention relates to spreader bars and like lifting devices. More particularly, the present invention relates to a spreader bar assembly having end portions which can be removably fitted to the ends of a section of pipe, for example, or a like structural member which has been precut to a desired length.
2. General Background
In the lifting of equipment such as for loading onto ships or for construction, a crane normally provides a single load line which branches at a bridle and attaches in two portions to an elongated bar known in the art as a spreader bar. The spreader bar then has one or more depending load lines lowered from it at each end which are affixed to a piece of equipment to be lifted. This apparatus per se and the use of spreader bars is generally known in the art.
Spreader bars are normally custom constructed to fit a piece of equipment of a given load and dimension, and thus cannot be reused except on a piece of equipment of similar dimension and equal or lesser load. Attempts have been made in various United States patents to teach a method for providing an adjustable spreader bar which could be used over a variety of spreader lengths.
In U.S. Pat. No. 4,128,267 entitled "Lifting Beam" there can be seen a lifting beam comprising an elongate member carrying one or more pivotally mounted hooks for engagement of a load to be lifted. A balance weight is provided on the hooks to lie on either side of the pivotal axis thereof so as to cause the hook to be biased into or from engagement of the load to be picked up or released when the beam is lowered on to same.
In U.S. Pat. No. 4,136,903 there can be seen a "Tire Lifting Apparatus" which comprises a master support sleeve, two movable arms slideably associated therewith, and two hook units pivotably connected to the arms for easy engagement with the inner rim of a tire.
A "Handling Beam for Heavy Elongate Objects" can be seen in U.S. Pat. No. 3,762,756 which comprises a simple and reliable missile handling beam assembly readily engageable with conventional missile supporting lug arrangements. The assembly does not impose any stress on the object being handled, since a lifting hook can be located in a position closest to the center of gravity of the load, hence the attitude of the object can be easily controlled during the lifting and lowering movements.
In U.S. Pat. No. 4,258,949 entitled "Extensible Spreader Frame for Cargo Containers" there can be seen an extensible lifting spreader frame comprising a pair of oppositely extending beam arms slideably received within a central pair of side-by-side connected sleeve beams. Beam cross arms at the outer ends of the sleeve beams mount twist-lock latching hooks at their opposite ends for attachment to the four socketed top corners of a cargo container to be lifted.
A "Sling Mounting Head" for use with a spacer element and mounting two members of a sling chain can be seen in U.S. Pat. No. 4,215,891. The sling mounting head has a body portion including a central section, and first and second end sections extending from the central section.
In U.S. Pat. No. 3,206,243 issued to B. F. Miles on Sep. 14, 1965, there is seen a "Spreader Bar" apparatus.
U.S. Pat. No. 3,010,751 entitled "Adjustable Lift Hooks" issued on Nov. 28, 1961 to E. J. Day, et al.
A "Sling Carrier" device is seen in U.S. Pat. No. 3,252,729 which issued on May 24, 1966, to R. A. Holmes.
Many of these devices are highly complex in nature and because of their construction would necessarily be limited to relatively small loads.
Thus, there is a need for a simple, easy to use, easy to construct spreader bar which could easily be adapted to a variety of load and dimensional situations.
3. General Discussion of the Present Invention
The present invention solves these prior art problems and shortcomings in a simple manner by providing a spreader bar assembly which utilizes a rigid elongated central support bar of uniform cross-section such as, for example, an elongated section of pipe which can be precut to a desired length. A pair of lifting eye assemblies are connected during the lifting operation at each respective end portion of the bar to form removable connection with the bar and also with an above supporting bridle line, each of the lifting eye assemblies comprising in part a socket of uniform cross-section receptive of one end of said bar therein and having a corresponding internal cross-section equal to or slightly larger than the external cross-section of the support bar. A stop is provided for limiting the degree of penetration of the support bar into the respective socket. In the preferred embodiment, the central support bar is an elongated section of cylindrical pipe and the sockets are cylindrical, being of an equal or slightly larger internal diameter to the external diameter of the section of pipe.
The sockets are preferably open ended at one end portion and terminate at an inner stop. A plate is affixed rigidly to the socket and extends downwardly and rearwardly therefrom away from the open end portion of the socket. At least one opening is provided in the plate whch is receptive of the bridle and lifting lines. If desired, a pair of spaced apart openings can be provided in the plate, one for the bridle line and one for the downwardly depending load line. The lift opening for the bridle lift line can be located concentric with the elongated support bar, eliminating the potential for bending moment in the bar regardless of the length of bridle used. Gusseting can be provided on the plate for stiffening the plate, with the guesseting in the preferred embodiment being affixed by welding, for example, to the end of the socket and tangent to the socket with the gusset plates crossing.
The openings can be reinforced by thickening at their periphery for added strength.
From the above, one skilled in the art will see that the end lifting eye assemblies are freely removable from the pipe and thus could be reused over and over again by the attachment to lengths of pipe of desired precut dimensions. It can be seen also that the present invention allows for the use of a wide variety of sling lengths during lift due to the positioning of the bridle line openings. This would provide a spreader bar of high structural integrity, capable of lifting very heavy loads on the order of, for example, several hundred tons yet lend itself to the variety of dimensional situations.
Thus, it is an object of the present invention to provide a spreader bar assembly which can be adapted to a variety of dimensional situations without having to reconstruct the entire bar with each lift.
Another object of the present invention is to provide a spreader bar assembly with removable end lifting portions which could be added to a desired central spreader bar portion of desired dimensions.
Another object of the present invention is to provide a spreader bar assembly which is highly versatile, easy to construct, and of high structural integrity.
Another object of the present invention is to provide a spreader bar which is not generally dependent upon a certain required sling length for lift, allowing for a wide variation in sling or bridle lengths.